Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Short Brother Model SD3-30 and SD3-SHERPA series airplanes. This proposal would require inspections of the vertical fin-to-tailplane joint to detect any loose bolts; and, if necessary, inspections to detect elongation of bolt holes, and replacement with new bolts, if necessary. Additionally, the proposal would require inspections of the upper shear angle to detect pulled or loose rivets, and replacement of the shear angle using new rivets, if necessary. This proposal is prompted by reports of loose bolts in the vertical fin-to-tailplane joint and pulled or loose rivets in an upper shear angle. The actions specified by the proposed AD are intended to prevent reduced structural integrity of the vertical fin to tailplane joint due to such discrepancies of the bolts or rivets.